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The impacts of abnormal weather and natural disasters on transport and strategies for enhancing ability for disaster prevention and mitigation
Journal Pre-proof The Impacts of Abnormal Weather and Natural Disasters on Transport and Strategies for Enhancing Ability for Disaster Prevention and Mitigation
Huapu Lu, Mingyu Chen, Wenbo Kuang PII:
S0967-070X(17)30361-X
DOI:
https://doi.org/10.1016/j.tranpol.2019.10.006
Reference:
JTRP 2250
To appear in:
Transport Policy
Received Date:
28 May 2017
Accepted Date:
18 October 2019
Please cite this article as: Huapu Lu, Mingyu Chen, Wenbo Kuang, The Impacts of Abnormal Weather and Natural Disasters on Transport and Strategies for Enhancing Ability for Disaster Prevention and Mitigation, Transport Policy (2019), https://doi.org/10.1016/j.tranpol.2019.10.006
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Journal Pre-proof The Impacts of Abnormal Weather and Natural Disasters on Transport and Strategies for Enhancing Ability for Disaster Prevention and Mitigation Huapu LU1, Mingyu CHEN2, Wenbo KUANG3 1,2,3
Department of Civil Engineering, Tsinghua University, Beijing, 100084, China 1 E-mail: [email protected] 2 E-mail: [email protected] 3 E-mail:[email protected]
Journal Pre-proof Abstract: Abnormal weather and natural disasters have become more frequent and serious around the world in recent years. Heavy rain, ice, snow, fog and haze impacts transport systems seriously and differently. Based on reviewing the relevant research on the prevention and control of traffic meteorological disasters at home and abroad, this study firstly illustrates the micro mechanism of different abnormal weathers’ influences on transport, and then analyzes cases of damage to transport system due to different abnormal weather conditions in China in recent years. Lastly, it discusses several key strategies, especially policy recommendations, for prevention of transport congestion and traffic accidents in abnormal bad weather. Keywords: Abnormal Weather; Traffic Flow Characteristics; Traffic Meteorology 1. INTRODUCTION Abnormal weather and natural disasters have had serious impacts on transport which influence human life and industry. Due to global warming, events of extreme weather have been increasing. According to the United Nations International Strategy for Disaster Reduction, between 1998 and 2017, climate disasters accounted for 91% of all 7255 recorded disasters in the whole world. Among them, floods were the most frequent, at 43% (Wallemacq and House, 2018). Meanwhile, the number of vehicles has been increasing significantly. In China, car ownership exceeded 200 million by 2017, more than double the level in 2011(Statistics, 2017). Therefore, if we do not take substantial measures, climate disasters will bring about serious damages to people’s mobility and life, and freight and logistics for industries, resulting in economic losses. However, citizens hope that the city will be sufficiently resilient to ensure all kinds of lifelines and that other supporting facilities can play roles in climate disasters. Thus, the aim of this paper is to provide a) more responsible policies for the national and local governments and b) hints for citizens to be aware of the risks of damages due to extreme weather in order to mitigate and adapt the influence on transport. The paper describes typical climate disaster phenomena and influences and then presents the micro mechanism of different abnormal weathers’ influences on transport. Next, it investigates evidential studies of the influence of typical extreme weathers such as heavy rain, ice and snow, fog and haze in China. Finally, it puts forward prevention strategies for transport congestion and accidents in abnormal bad weather. 2. POSITIONING OF THIS STUDY 2.1 Literature Review 2.1.1 Research on evidences of damages on traffic by climate disasters Natural disasters seriously influence people’s daily lives and industrial 1
Journal Pre-proof production via damages in transport. When cities and regions have heavy rainfall, without a proper sewerage system, water will accumulate on the road surface. Even worse, roads may be flooded and stuck. When the temperature drops to a certain level, transport is exposed to snowfall and the road may be frozen. When fog or haze occurs, visibility declines dramatically, making travel difficult. It is not easy for people to drive or walk in extreme weather. It not only takes a long time to commute, but commuters are also more prone to traffic congestion and even accidents. Therefore, people are injured or even killed by climate disasters. In addition to impacts on people, their impacts on logistics and infrastructure can also result in economic losses. The effect of weather on transport is a comprehensive and complicated problem. It concerns not only physical changes, but also drivers’ subjective actions and mindsets. As a result, as we can hardly analyze the relationship between bad weather and transport theoretically, researchers often use the empirical studies to illustrate their relationship. For rainfall, Okamoto(2004) classified rainfall intensity and analyzed their influences on traffic flow based on Tomei Expressway data. For example, the capacity decreases by 33%, when the rainfall intensity is 0.49-0.96cm/hour. In China, Yang et al. (2010) plotted Shanghai’s traffic flow-density-speed curve on rainy and snowy days. They concluded that on heavily rainy days (>6.25mm/h), road capacity dropped 13%-15%, while on heavily snowy days (>12mm/h) it dropped 15%-22%. According to Guangzhou's rainfall data, Xu et al. (2013) found that rainfall had a great impact on the level-of-service of road network, especially on the evening peak. The weighted speed dropped 4.4% -15.6%. For ice and snow, based on the traffic volume and traffic accident statistics in Wuhan, Li and Wan (2000) estimated the economic losses of traffic accidents caused by fog in Wuhan at about 7 million RMB Yuan. Cheng et al. (2011) observed the friction coefficient with instruments and revealed that the friction coefficient of snow-covered roads is 0.18 -0.31, and that of ice-snow mixed roads is 0.06-0.17, which decreases with the increase of atmospheric humidity. For fog and haze, Zhao et al. (2010) summarized their impacts on expressway driving. Because expressways are characterized by large traffic flows and fast driving speeds, fog and haze often cause chain reactions, and eventually form serious traffic accidents of multi-car rear-end collisions. Through experiments, Mueller and Trick (2012) discovered that in the haze, drivers’ visual distance decreases, and vehicle distance is easily misjudged, which leads to an increase in the rate of traffic accident. Most of these studies describe the weather phenomena and the results in traffic. However, several factors were not taken into account such as infrastructure situations, local characteristics and policies at that time. In this paper, for each abnormal weather event, we will analyze the local infrastructure, related transport and traffic characteristics and policies in detail.
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Journal Pre-proof 2.1.2 Research on policies for the prevention of disasters in transport and traffic In developed countries such as Europe, America and Japan, research on traffic and meteorology started earlier and were also more in-depth, especially in the field of road meteorological disasters, due to their motorway networks and advanced road management information systems. Many research results have been put into practical use. For example, Sweden, Denmark, the United Kingdom and Germany established manual real-time monitoring and forecasting systems in the early 80s of the last century to provide support for road maintenance for relevant departments. (Shao and J. Lister, 1996, Hertl and Schaffar, 1998, Gustavsson, 1999). In China， it has not been long since research on meteorological influence on traffic came into being. Despite a late start, it has undergone unprecedented expansion during the last few years, which benefited from the progress of meteorological observation technology, the rapid development of motorway traffic construction, and the increasing demand for traffic meteorological services. At present, in most provinces in China, transport departments and meteorological departments have carried out a variety of traffic meteorological services in accordance with the local traffic weather and climate characteristics. The Beijing Meteorological Bureau began to develop traffic meteorological services in the 1990s, and it established meteorological monitoring stations on significant expressways (Badaling expressway, airport expressway, etc.) in 2005. Combined with the introduction of the abnormal weather warning project in Beijing, by the end of 2009, Beijing had 28 traffic meteorological monitoring networks, equipped mainly in the ring roads and the major motorways (Ding and Li, 2009, ZHANG et al., 2007). However, because meteorological services are still in the development stage in China, the study of the interaction between meteorology and traffic is in the primary stage. Firstly, although there are several facilities such as metrological stations and visibility detectors along roads, only some provinces and cities have relatively sophisticated systems for deployment analysis and forecasting, which are mostly supported by imported equipment. Secondly, they are on general-purpose. At present, the elements in road traffic meteorological observation are general observations, which cannot meet the diversified and sophisticated demands of traffic management. 2.2 Framework of this study As shown in the Figure1, climate disasters impact road conditions and visibility, resulting in a reduction of road capacity and average speed. Rain, ice and snow, fog and haze all have obvious negative influences on transport, but they affect drivers’ behaviors, road conditions, and vehicle performances differently. However, policies can be taken in two phases to ease their impacts: mitigation policies can be implemented before disasters, and adaptation policies are intended to alleviate the impacts after disasters occur. Among these policies, education and pre-caution systems are vital methods. It is 3
Journal Pre-proof critical to establish a mechanism that enable young people to take actions (Hayashi and Suzuki, 2016). By enlightening people’s awareness of danger and teaching people how to protect themselves before and in extreme weather, these policies can effectively help people avoid casualties. Pre-caution systems afford essential information both for travelers and rescue organizations. Travelers can choose safe modes and areas, and rescue organizations can accurately grasp the overall situation and implement rescues more effectively. It is also necessary to possess a well-functioning infrastructure including sewerage and pumping systems before disasters, so the accumulation of rainfall and snowfall can be quickly relieved during disasters. When infrastructure is out of work, for example, heavy snow can crash power supply lines, possibly leading to street lights and signal lights failing, the policemen including traffic and public security departments need take actions in time.
(a) Rain
(b) Ice and Snow
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(c) Fog Figure 1 Micro mechanism of different abnormal weather’s influence on transport
To make transport and traffic systems more resilient, in this paper we will investigate several case studies in China through their weather phenomena and results, and then give corresponding detailed policy recommendations. 3. CASES OF TRAFFIC STANDSTILL CAUSED WEATHER IN RECENT YEARS IN CHINA
BY
ABNORMAL
3.1 Case Study Concerning the Impact of Heavy Rain on Transport 3.1.1 Phenomena Evidences Rain mainly affects transport in three aspects. Firstly, light rain decreases the friction factor between the road surface and tires. Due to the slippery road surface, drivers need to slow down. Secondly, low visibility caused by heavy rain may force drivers to slow down their cars as well. Lastly, when rainfall is concentrated and intense, it may flood the roads. In this case, transport would be affected very seriously. There are a lot of cases where heavy rain influences transport. On July 18th, 2007, Jinan city in Shandong province faced a violent storm of short duration but heavy intensity. The rainfall began at 17 o’clock and lasted for about 4 hours. The maximum hourly rainfall reached 151mm, while the maximum two-hour and three-hour rainfall were 167.5mm and 180mm respectively, which were the maximum amounts in recorded history. The city’s low-lying areas were flooded seriously, and most roads were flooded and broke down. 34 people died, and 171 people were injured in the disaster, and 800 vehicles were damaged. The storm also destroyed about 14,000 square meters of roads and more than 500 metal manhole covers in physical losses and about 1.32 billion RMB Yuan economic losses(Wei, 2011a). In Jinan, elevation decreases falls from south to north. Accordingly, main roads also have a north-south orientation. Unfortunately, when the violent storm hit the city, these north-south main roads became flood channels where rainfall converged at the mountains in the south and was then flushed to the north–the city’s downtown (Figure 2). At the intersection of a north-south main road, Lishan Road, and a west-east main 5
Journal Pre-proof road, West Wenhua Road, the flood was more than 1m deep which flushed even 300 kilogram stones away near the safety island of the intersection. When the wave hit road lamps, it reached a height of 2 meters. At the terrain fall from south to north in along Lishan Road, the flood raged more. At the intersection of Lishan Road and Leyuan Road, all vehicles broke down, and many people were knocked down by the raging torrent (Figure 3). The torrent accumulated more flooding, flushed to the north and finally hit the city center – Quancheng Square. An area of almost 10 km2 near Quancheng Square was flooded after the storm. According to statistics, most of the storm’s victims and injured people were around this area (Cao, 2007).
Figure 2 Heavy rain made main roads in Jinan became flood channels, 2007 (Source: Xinhua News Agency)
Figure 3 Heavy rain made Jinan’s transport system came into paralysis, 2007 (Source: the internet)
Jinan is not the only city which suffered from a heavy storm. On July 21st, 2012, China’s capital city Beijing was hit by a violent storm. The average rainfall reached 164mm, and the maximum rainfall was at Fangshan district, which reached 460mm. Also, heavy rain flooded the city center and led to chaos in regard to transport in the city center. In mountain areas, lots of rural roads were blocked. In the city center, there were more than 95 road links blocked by deep ponding. Figure 4 illustrates the distribution of the main ponded areas in Beijing. We can conclude that Beijing’s 2nd, 3rd, 4th and 5th ring roads were blocked. Most ponded areas were in the rapid ring roads and concave-type overpasses, which made the city’s arterial roads come to a standstill (Figures 4, 5, and 6).
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Figure 4 Flood ponding distribution in Beijing after heavy rainfall in July 21st, 2012 (Source: the internet) *Numbers in the figure show the flooded road sections.
Figure 5 Blocked road under Lianhua Bridge
Figure 6 Motorway G4 Changyang section was
because of the flood (Source: Xinhua News
blocked by flood (Source: Xinhua News Agency)
Agency)
In addition to the ground road system, rail transport also came under serious crisis. Because electrical devices were submerged, the Airport Express line’s rail trains lost their power supply. In some subway stations, such as Majiapu and Jiaomenxi, flood water flushed in reverse into the stations, which forced them out of service (Wei, 2012). 3.1.2 Policies The limitation of Jinan's sewerage system’s capacity and the unwise decision of closing the water gates aggravated the disaster. Firstly, in the old urban area of Jinan, the sewerage system was built several decades ago. The main drainage pipe’ diameter is only 300mm. The rainfall was far beyond the sewerage system’s capacity that day. 7
Journal Pre-proof Secondly, to promote tourism in Jinan, the city moat’s water gates were closed to preserve water in the moat. Before the storm, the water gates were still closed. When people opened the water gates, the gates were blocked up by boats from upstream. As all flood channels were either blocked up or up to the limitation, the flood finally stopped at Quancheng Square(Wei, 2011a). Moreover, people were totally unaware of the danger. When the rainstorm happened, people still hid in the busy underground supermarket to shelter themselves from the rain. Outside the door, there was a moat that was already flooding. When the moat began to pour into the underground supermarket , the crowd began to flee in complete disorder. As that of Jinan, Beijing's sewerage system had been in poor condition. Investment in an urban sewerage system cannot bring immediate benefits and achievements to the government, so local governments instead prefer to invest public funds in municipal infrastructure related to real estate and industrial projects. Also, people in Beijing were ignorant about the turbulent flood caused by the storm. People were washed away or fell into wells almost in a matter of moments on the road; others were too late to respond to rescue. Learning from these disasters caused by heavy rain, we recommend the following targeted policies. For mitigation policies, first as a hard infrastructure, the renovation of the drainage system is necessary. The capacities of sewerage systems in Jinan and Beijing have not kept up with rainfall drainage needs, which is the leading cause for water accumulation. For an international metropolis like Beijing, flood prevention infrastructure and pumping system must be in accordance with the development, otherwise, the casualties and economic losses caused by heavy rain will be huge. Also, some disaster prevention facilities such as sandbags could be prepared in subway stations. Second as a soft measure, great importance should be attached to education, especially for women, children and the elderly, who are vulnerable in climate disasters. Continuous education and enlightenment can plant in people’s mind a good awareness to avoid the future possible big risk. For adaptation policies, the first is to establish a sound pre-caution system. During the rainy season, rain time and location forecasts could be spread through mass media like TV news, WeChat and Micro-blog to alert people. Maps of flooded roads could help travelers to avoid choosing routes with low-lying areas and rescue organizations to take actions more effectively. Then, police officers need to play a timely role. Traffic policemen should direct traffic in time when congestion occurs, especially when street lights and signal lights fail. The security policemen should rescue the car owners in time when they are trapped during heavy rain. Next, it is also necessary to publicize self-help knowledge. Through mass media, government and organization officials could publish self-help common sense guidebooks, etc., Even a five-minute reading of these texts could save a life when trapped in a car by floods.
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Journal Pre-proof 3.2 Case Study Concerning the Impact of Ice and Snow Weather on Transport 3.2.1 Phenomena Evidences Compared to heavy rain, the case of ice and snow weather can influence transport both in spatially wider areas and temporally longer periods. Ice and snow weather mainly decreases friction between road surface and tires. In south China, the road system has frequently suffered from ice rain in winter in recent years. Road surfaces are covered by about 2mm thick ice when ice rain comes. It often causes serious traffic accidents, as drivers can hardly notice the ice surface. Even though accidents could be avoided via drivers’ alerts, road capacity decreases considerably. From January 10th to February 2nd, 2008, China’s southern region suffered from serious ice and snow weather four times. The rare weather hit nearly 20 provinces. The weather seriously damaged transport infrastructure, energy supply and power transmission devices and agricultural production. In regard to provincial and intercity transport, because the ice and snow weather occurred just during the Spring Move, a time of heavy passenger transport around Chinese Lunar New Year, passengers on their way hometowns were seriously influenced by the bad weather. Due to electrical conductor icing, trains on Beijing-Guangzhou railway were stuck because of power loss. At one point, there were about 300,000 passengers at the Guangzhou railway station. Motorways in China’s southern region were mostly closed due to the bad weather. Influenced by motorway closings, national roads and provincial roads suffered much more vehicles beyond capacity (Figure 7 and Figure 8). At the most serious time, 40,000km of over 21 national roads were in the traffic jam, which caused thousands of people and vehicles to be stuck on their journeys. Air transport was also profoundly influenced by bad weather. Airport runways and aircrafts were covered by thick ice, and 19 airports in the southern region were closed for a long time (Zhang, 2013).
Figure 7 Traffic jams at Wuhan Yangtze River
Figure 8 Jingzhu Motorway Hunan section was in
Bridge Wuchang side due to ice and snow
an entirely standstill due to ice cover on roads,
weather, January 14th, 2008 (Source: Xinhua
January 30th, 2008 (Source: Xinhua News
News Agency)
Agency)
With regard to urban transport, icing weather covered road surface and made them extremely slippery, especially at bridges. As bridges are always the arterial 9
Journal Pre-proof channel in urban transport systems, once they are closed, the whole transport system operation stops. In mid-January 2008, many bridges crossing the Yangtze River and the Xiang River, such as the Jiujiang Yangtze River Bridge and the Changsha Xiang River Bridge, were closed for some periods. Each time the authorities closed a bridge, hundreds of vehicles were blocked. Besides ice cover, snow cover also largely influences the transport systems. In January 2010, the Aletai and Tacheng regions in Xinjiang province were hit by strong snow storm four times continuously, which happens only once in 60 years. Even into March 2010, the regions were suffering from heavy snow and strong wind again (Wei, 2011b). Heavy snow and strong wind mainly influence transport on national roads and provincial roads. Because of Xinjiang’s side land, yet sparse population distribution, snow cover on national and provincial roads could not be cleared easily (Figure 9 and Figure 10). On March 7th, 2010, in Yumin County, provincial roads No. 222 and No. 317 to the capital city of Urumqi were closed due to snow cover. All roads connecting the Yumin County center to its 30 villages were blocked. In March 8th in Fuyun County, more than 200 vehicles and 500 people were blocked on national road No. 216. On the following day, all roads passing Yumin County were blocked, and the county became an isolated island (Xiao, 2010).
Figure 9 Provincial road was blocked by snow, March 2010 ( Source: Urumqi online)
Figure 10 Heavy snow with strong wind buried tracks at Aikenda mountain slope in Xinjiang, 2010 ( Source: China Youth Daily)
3.2.2 Policies In the face of ice and snow, people often can only wait for them to melt away. Also, governments prefer to shut down some motorways and bridges to avoid traffic accidents, which brings pressure on the remaining road networks, increasing traffic congestions and making it difficult for people to travel. Having learnt from the cases of disasters caused by ice and snow, we propose the following targeted policies. For mitigation policies, first of all, intelligent means can be used on some critical bridges and motorways. Melting snow and ice by itself and removing it through drainage systems is a long process. Human intervention will accelerate this process and shorten the scope and time of traffic impact. Sensors can be set up on the 10
Journal Pre-proof road surface to collect real-time information of ice and snow, then deice and melt snow using automatic snow-melting agent spraying systems. Such timely measures provide security guarantees without having to close major motorways and bridges. Also, education needs to be emphasized as we recommended in the case of rain disasters, to make people aware of the dangers of ice and snow. For adaptation policies, first of all, as hard measures, snow-chains or snow tires could be installed for safety. Slippery roads may cause serious accidents, and this measure could ease the decrease of friction. Other policies are similar to those for rain disasters. As soft measures, pre-caution system is an essential measure. Snow time and location forecasts, and icy road maps are helpful to travelers and the agents responsible for cleaning ice and snow on roads. Traffic policemen also need to guide people and cars in time, and to conduct accident rescue. Next, safety education could be increased by using media propaganda to spread messages such as “Obey the traffic rules”, “Slow down and keep a safe distance from the vehicles ahead” and “During snow days, do not walk with hands in pockets due to the cold, it is easy to lose balance.” 3.3 Case Study Concerning the Impact of Fog and Haze on Transport 3.3.1 Phenomena Evidences Fog and haze weather mainly affects air transport, motorways and urban expressways. They mainly affect visibility, which may slow down vehicles and reduce road capacity and average speed accordingly. When obstacles are in front of travelers because of the limited visible distance, accidents are natural to occur. In 2013, from January to February, northern China faced long lasting fog and haze weather. In January alone, there were 27 fog and haze weather days out of 31days. One of the most seriously influenced provinces was Hebei province. In January, from the 11th to 17th, 21st to 24th, and 27th to 30th, heavy fog continuously hit the area. In the capital city Shijiazhuang, the fog and haze lasted for more than 20 hours on January 22nd. Heavy fog and haze led to low visibility down to less than 100 meters, for the whole day. The airport and all 22 motorways were entirely closed. All flights were canceled. In the city center, the number of traffic accidents increased a lot, and average speed on the road network was notably lower than its usual levels (Tang, 2013). Beijing was also influenced by serious fog and haze in January, 2013. Especially on January 31st, heavy fog hit the city along with ice and snow. From 12a.m. to 11a.m. alone, there were more than 2000 traffic accidents. Although the accidents were mostly light, they triggered a chaos in the whole transport system. For example, on the overhead road from Wangjing to Taiyanggong which is about 3km long, more than 100 cars were involved in a pileup accident. There were 12 accidents on Jingping motorway from the 44km point to the 45km point. On North 4th ring road, wet road and bad visibility caused 12 accidents involving 40 cars, which caused more than 2 hours of serious congestion in the direction from east to west (Yan, 2013). 11
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Figure
11
Congestion
at
Motorway
G4
Figure 12 100 cars pileup at overhead road from
Shijiazhuang Entrance due to heavy fog and haze,
Wangjing to Taiyanggong, Beijing, January,
January 2013(Source: China News Agency)
2013 (Source: Jinwan internet community)
3.3.2 Policies For fog and haze, most of the policies taken by the government involve closing some high-pollution factories to avoid worse visibility, but this did not work very well. Having learned from the cases of disasters caused by fog and haze, we propose the following targeted policies. For mitigation policies, fog is difficult to be eliminated by human means, so the best way is to awaken people to the dangers of fog and haze through mass media. To reduce carbon emissions, governments should advocate people to travel by public transport as a preferred way. For adaptation policies, first of all, timely vehicle glass defogging by cold air could ease the impacts of low visibility. Other policies (policemen, pre-caution system, education) are similar to policies for rain and snow disasters. Information about reasonable use of car lights, speed limit, and route choice could be advised before fog and haze. What’s more, do not drive on the roadside, to avoid hitting the fence and collision with vehicles parked in the emergency lane.
4. STRATEGIES AND POLICIES FOR TRANSPORT CONGESTION AND ACCIDENTS PREVENTION IN ABNORMAL BAD WEATHER To continuously improve the level of traffic safety, and ensure the efficiency of the transport systems in abnormal bad weather, relevant departments must seize two priorities: one is to create a reliable transport system, the second is to achieve a deep integration of traffic and meteorology. Some recommendations are as follows: 4.1 Create a reliable transport system On the one hand, even though abnormal weather may cause congestion in a large area, congestion is caused by chaos in several intersections and road links. For 12
Journal Pre-proof instance, in Beijing, heavy storms in the summer always cause floods on main roads. Under concave-type overpasses, such as the Lianhua Bridge and the Guangqu gate overpass, floods block the traffic. These critical points block the whole road and paralyze the whole transport system into. Therefore, via in-depth analysis of essential aspects and transport network planning based on reliability, city disaster prevention and mitigation ability could be improved. Simultaneously, a detailed evaluation of the current transport system is also necessary. Workers and devices should be arranged in advance at critical points for immediate responses when disaster comes On the other hand, serious transport paralyzes are always caused by break-down of transport infrastructure. Therefore, proper improvement of infrastructure design and planning standards would fundamentally improve the ability of disaster prevention and mitigation in the transport field.
4.2 Achieving a deep integration of traffic and meteorology Traffic operation and safety are closely related to the meteorological department. Based on big data cloud computing, traffic departments should vigorously promote the full integration of traffic and meteorological data. In the view of personalized and diversified traffic needs, providing accurate traffic meteorological services, including monitoring, forecasting, warning and automatic processing is essential. Efforts can be carried on regarding the following aspects: (1) Formulate a specific development strategy at the national level as soon as possible. (2) Steadily increase investment in the field of traffic meteorological monitoring, and enhance the coordination of traffic and meteorological departments. (3) Speed up the step of the construction of traffic meteorological information collection and early warning system which can a) judge and evaluate weather conditions and transport infrastructure performance accurately, and b) respond rapidly to the problems, warning the relevant departments as well as the road users and automatic processing. (4) Strengthen the standardization work and develop a common specification to ensure the connection between the associated equipment and achieving the mutual transmission of information.
4.3 Prepare Complete Pre-arranged Plans for Abnormal Issues Nowadays, in China, most pre-arranged plans focus on traffic accident rather than on traffic congestion caused by extreme weather. In 2008, when heavy ice rain and snow hit southern China, some provinces had no pre-arranged plan against ice and snow weather at all. The absence of plans not only created confusion among different government departments, but also created delays and lost precious time for 13
Journal Pre-proof rescuers. When disasters come, each government department should understand and keep its own duties and then share valuable information with other departments. Based on pre-arranged plans, leader groups should be set immediately. On the one hand, to keep rapid responses, each region and department’s responsibility should be clear and defined in advance. On the other hand, possible risk points should be thoroughly estimated. For each possible risk point, a corresponding strategy is necessary, to keep emergency response productive. 5. CONCLUSION Having examined the case studies, we have found the following typical phenomena and mechanisms of disasters influencing on the transport and traffic. 1) Heavy rain: slippery road surface and low visibility made drivers slow down. Moreover, without well-functional sewerage systems, roads were blocked by deep ponding. 2) Ice and snow: due to the influence of motorway closures and the decrease of friction between road and tire, ordinary roads were more prone to traffic congestion. 3) Fog and haze: low visibility always caused continuous rear-end accidents. After examining the mechanisms, the following two-phase policies are recommended. Mitigation policies are to be implement before disasters, and adaptation policies are alleviate the impacts after the disaster occurrence. a) Mitigation policies for infrastructure: enhance disaster prevention facilities (e.g. sandbags), sewerage system, pumping systems and intelligent snow-melting agent spraying system. b) Mitigation policies for people: introduce pre-education methods. They can be propagated through mass media such as TV news, WeChat and Micro-blog. c) Adaptation policies for infrastructure: strengthen pre-caution systems, which will be a guide for travelers, rescue organizations and governments. d) Adaptation policies for people: increase safety education through media propaganda to encourage self-help and mutual help. Police officers need to play a timely role in traffic guidance and rescue. REFERENCES 1. 2.
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Journal Pre-proof 19. YAN, B. (2013). Heavy traffic accidents on Beijing's roads [Online]. CCTV News. Available: http://news.cntv.cn/2013/02/01/ARTI1359662277230464.shtml [Accessed 06-12 2019]. (in Chinese) 20. YANG, Z., LIN, Y. & GAO, X. (2010). Urban Expressway Capacity Under Adverse Weather Conditions. Journal of Transport Information and Safety, 28, 75-78. (in Chinese) 21. ZHANG, C., ZHANG, L.-N., CHENG, C.-L. & WANG, B.-Z. (2007). Research Status and Future Trend of Expressway Meteorological Forecast System. Journal of Tropical Meteorology 652-658. (in Chinese) 22. ZHANG, H. (2013). Snow Disaster in Southern China in 2008 [Online]. CAIXIN.COM. Available: http://special.caixin.com/event_0110/ [Accessed 06-14 2019]. (in Chinese) 23. ZHAO, H., WANG, W., LI, Z. & WANG, Y. (2010). Adverse Effects of Fog on China's Transportation and Countermeasures. Journal of meteorology and environment, 26, 58-62. (in Chinese)
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Journal Pre-proof Highlight 1. Classifying different weather conditions and pre-arranged plans are very critical. 2. To create a reliable transportation system is a priority to disaster prevention. 3. Mitigation and adaptation policies can ease the impacts of abnormal bad weather.
Huapu Lu, Mingyu Chen, Wenbo Kuang PII:
S0967-070X(17)30361-X
DOI:
https://doi.org/10.1016/j.tranpol.2019.10.006
Reference:
JTRP 2250
To appear in:
Transport Policy
Received Date:
28 May 2017
Accepted Date:
18 October 2019
Please cite this article as: Huapu Lu, Mingyu Chen, Wenbo Kuang, The Impacts of Abnormal Weather and Natural Disasters on Transport and Strategies for Enhancing Ability for Disaster Prevention and Mitigation, Transport Policy (2019), https://doi.org/10.1016/j.tranpol.2019.10.006
This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. © 2019 Published by Elsevier.
Journal Pre-proof The Impacts of Abnormal Weather and Natural Disasters on Transport and Strategies for Enhancing Ability for Disaster Prevention and Mitigation Huapu LU1, Mingyu CHEN2, Wenbo KUANG3 1,2,3
Department of Civil Engineering, Tsinghua University, Beijing, 100084, China 1 E-mail: [email protected] 2 E-mail: [email protected] 3 E-mail:[email protected]
Journal Pre-proof Abstract: Abnormal weather and natural disasters have become more frequent and serious around the world in recent years. Heavy rain, ice, snow, fog and haze impacts transport systems seriously and differently. Based on reviewing the relevant research on the prevention and control of traffic meteorological disasters at home and abroad, this study firstly illustrates the micro mechanism of different abnormal weathers’ influences on transport, and then analyzes cases of damage to transport system due to different abnormal weather conditions in China in recent years. Lastly, it discusses several key strategies, especially policy recommendations, for prevention of transport congestion and traffic accidents in abnormal bad weather. Keywords: Abnormal Weather; Traffic Flow Characteristics; Traffic Meteorology 1. INTRODUCTION Abnormal weather and natural disasters have had serious impacts on transport which influence human life and industry. Due to global warming, events of extreme weather have been increasing. According to the United Nations International Strategy for Disaster Reduction, between 1998 and 2017, climate disasters accounted for 91% of all 7255 recorded disasters in the whole world. Among them, floods were the most frequent, at 43% (Wallemacq and House, 2018). Meanwhile, the number of vehicles has been increasing significantly. In China, car ownership exceeded 200 million by 2017, more than double the level in 2011(Statistics, 2017). Therefore, if we do not take substantial measures, climate disasters will bring about serious damages to people’s mobility and life, and freight and logistics for industries, resulting in economic losses. However, citizens hope that the city will be sufficiently resilient to ensure all kinds of lifelines and that other supporting facilities can play roles in climate disasters. Thus, the aim of this paper is to provide a) more responsible policies for the national and local governments and b) hints for citizens to be aware of the risks of damages due to extreme weather in order to mitigate and adapt the influence on transport. The paper describes typical climate disaster phenomena and influences and then presents the micro mechanism of different abnormal weathers’ influences on transport. Next, it investigates evidential studies of the influence of typical extreme weathers such as heavy rain, ice and snow, fog and haze in China. Finally, it puts forward prevention strategies for transport congestion and accidents in abnormal bad weather. 2. POSITIONING OF THIS STUDY 2.1 Literature Review 2.1.1 Research on evidences of damages on traffic by climate disasters Natural disasters seriously influence people’s daily lives and industrial 1
Journal Pre-proof production via damages in transport. When cities and regions have heavy rainfall, without a proper sewerage system, water will accumulate on the road surface. Even worse, roads may be flooded and stuck. When the temperature drops to a certain level, transport is exposed to snowfall and the road may be frozen. When fog or haze occurs, visibility declines dramatically, making travel difficult. It is not easy for people to drive or walk in extreme weather. It not only takes a long time to commute, but commuters are also more prone to traffic congestion and even accidents. Therefore, people are injured or even killed by climate disasters. In addition to impacts on people, their impacts on logistics and infrastructure can also result in economic losses. The effect of weather on transport is a comprehensive and complicated problem. It concerns not only physical changes, but also drivers’ subjective actions and mindsets. As a result, as we can hardly analyze the relationship between bad weather and transport theoretically, researchers often use the empirical studies to illustrate their relationship. For rainfall, Okamoto(2004) classified rainfall intensity and analyzed their influences on traffic flow based on Tomei Expressway data. For example, the capacity decreases by 33%, when the rainfall intensity is 0.49-0.96cm/hour. In China, Yang et al. (2010) plotted Shanghai’s traffic flow-density-speed curve on rainy and snowy days. They concluded that on heavily rainy days (>6.25mm/h), road capacity dropped 13%-15%, while on heavily snowy days (>12mm/h) it dropped 15%-22%. According to Guangzhou's rainfall data, Xu et al. (2013) found that rainfall had a great impact on the level-of-service of road network, especially on the evening peak. The weighted speed dropped 4.4% -15.6%. For ice and snow, based on the traffic volume and traffic accident statistics in Wuhan, Li and Wan (2000) estimated the economic losses of traffic accidents caused by fog in Wuhan at about 7 million RMB Yuan. Cheng et al. (2011) observed the friction coefficient with instruments and revealed that the friction coefficient of snow-covered roads is 0.18 -0.31, and that of ice-snow mixed roads is 0.06-0.17, which decreases with the increase of atmospheric humidity. For fog and haze, Zhao et al. (2010) summarized their impacts on expressway driving. Because expressways are characterized by large traffic flows and fast driving speeds, fog and haze often cause chain reactions, and eventually form serious traffic accidents of multi-car rear-end collisions. Through experiments, Mueller and Trick (2012) discovered that in the haze, drivers’ visual distance decreases, and vehicle distance is easily misjudged, which leads to an increase in the rate of traffic accident. Most of these studies describe the weather phenomena and the results in traffic. However, several factors were not taken into account such as infrastructure situations, local characteristics and policies at that time. In this paper, for each abnormal weather event, we will analyze the local infrastructure, related transport and traffic characteristics and policies in detail.
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Journal Pre-proof 2.1.2 Research on policies for the prevention of disasters in transport and traffic In developed countries such as Europe, America and Japan, research on traffic and meteorology started earlier and were also more in-depth, especially in the field of road meteorological disasters, due to their motorway networks and advanced road management information systems. Many research results have been put into practical use. For example, Sweden, Denmark, the United Kingdom and Germany established manual real-time monitoring and forecasting systems in the early 80s of the last century to provide support for road maintenance for relevant departments. (Shao and J. Lister, 1996, Hertl and Schaffar, 1998, Gustavsson, 1999). In China， it has not been long since research on meteorological influence on traffic came into being. Despite a late start, it has undergone unprecedented expansion during the last few years, which benefited from the progress of meteorological observation technology, the rapid development of motorway traffic construction, and the increasing demand for traffic meteorological services. At present, in most provinces in China, transport departments and meteorological departments have carried out a variety of traffic meteorological services in accordance with the local traffic weather and climate characteristics. The Beijing Meteorological Bureau began to develop traffic meteorological services in the 1990s, and it established meteorological monitoring stations on significant expressways (Badaling expressway, airport expressway, etc.) in 2005. Combined with the introduction of the abnormal weather warning project in Beijing, by the end of 2009, Beijing had 28 traffic meteorological monitoring networks, equipped mainly in the ring roads and the major motorways (Ding and Li, 2009, ZHANG et al., 2007). However, because meteorological services are still in the development stage in China, the study of the interaction between meteorology and traffic is in the primary stage. Firstly, although there are several facilities such as metrological stations and visibility detectors along roads, only some provinces and cities have relatively sophisticated systems for deployment analysis and forecasting, which are mostly supported by imported equipment. Secondly, they are on general-purpose. At present, the elements in road traffic meteorological observation are general observations, which cannot meet the diversified and sophisticated demands of traffic management. 2.2 Framework of this study As shown in the Figure1, climate disasters impact road conditions and visibility, resulting in a reduction of road capacity and average speed. Rain, ice and snow, fog and haze all have obvious negative influences on transport, but they affect drivers’ behaviors, road conditions, and vehicle performances differently. However, policies can be taken in two phases to ease their impacts: mitigation policies can be implemented before disasters, and adaptation policies are intended to alleviate the impacts after disasters occur. Among these policies, education and pre-caution systems are vital methods. It is 3
Journal Pre-proof critical to establish a mechanism that enable young people to take actions (Hayashi and Suzuki, 2016). By enlightening people’s awareness of danger and teaching people how to protect themselves before and in extreme weather, these policies can effectively help people avoid casualties. Pre-caution systems afford essential information both for travelers and rescue organizations. Travelers can choose safe modes and areas, and rescue organizations can accurately grasp the overall situation and implement rescues more effectively. It is also necessary to possess a well-functioning infrastructure including sewerage and pumping systems before disasters, so the accumulation of rainfall and snowfall can be quickly relieved during disasters. When infrastructure is out of work, for example, heavy snow can crash power supply lines, possibly leading to street lights and signal lights failing, the policemen including traffic and public security departments need take actions in time.
(a) Rain
(b) Ice and Snow
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(c) Fog Figure 1 Micro mechanism of different abnormal weather’s influence on transport
To make transport and traffic systems more resilient, in this paper we will investigate several case studies in China through their weather phenomena and results, and then give corresponding detailed policy recommendations. 3. CASES OF TRAFFIC STANDSTILL CAUSED WEATHER IN RECENT YEARS IN CHINA
BY
ABNORMAL
3.1 Case Study Concerning the Impact of Heavy Rain on Transport 3.1.1 Phenomena Evidences Rain mainly affects transport in three aspects. Firstly, light rain decreases the friction factor between the road surface and tires. Due to the slippery road surface, drivers need to slow down. Secondly, low visibility caused by heavy rain may force drivers to slow down their cars as well. Lastly, when rainfall is concentrated and intense, it may flood the roads. In this case, transport would be affected very seriously. There are a lot of cases where heavy rain influences transport. On July 18th, 2007, Jinan city in Shandong province faced a violent storm of short duration but heavy intensity. The rainfall began at 17 o’clock and lasted for about 4 hours. The maximum hourly rainfall reached 151mm, while the maximum two-hour and three-hour rainfall were 167.5mm and 180mm respectively, which were the maximum amounts in recorded history. The city’s low-lying areas were flooded seriously, and most roads were flooded and broke down. 34 people died, and 171 people were injured in the disaster, and 800 vehicles were damaged. The storm also destroyed about 14,000 square meters of roads and more than 500 metal manhole covers in physical losses and about 1.32 billion RMB Yuan economic losses(Wei, 2011a). In Jinan, elevation decreases falls from south to north. Accordingly, main roads also have a north-south orientation. Unfortunately, when the violent storm hit the city, these north-south main roads became flood channels where rainfall converged at the mountains in the south and was then flushed to the north–the city’s downtown (Figure 2). At the intersection of a north-south main road, Lishan Road, and a west-east main 5
Journal Pre-proof road, West Wenhua Road, the flood was more than 1m deep which flushed even 300 kilogram stones away near the safety island of the intersection. When the wave hit road lamps, it reached a height of 2 meters. At the terrain fall from south to north in along Lishan Road, the flood raged more. At the intersection of Lishan Road and Leyuan Road, all vehicles broke down, and many people were knocked down by the raging torrent (Figure 3). The torrent accumulated more flooding, flushed to the north and finally hit the city center – Quancheng Square. An area of almost 10 km2 near Quancheng Square was flooded after the storm. According to statistics, most of the storm’s victims and injured people were around this area (Cao, 2007).
Figure 2 Heavy rain made main roads in Jinan became flood channels, 2007 (Source: Xinhua News Agency)
Figure 3 Heavy rain made Jinan’s transport system came into paralysis, 2007 (Source: the internet)
Jinan is not the only city which suffered from a heavy storm. On July 21st, 2012, China’s capital city Beijing was hit by a violent storm. The average rainfall reached 164mm, and the maximum rainfall was at Fangshan district, which reached 460mm. Also, heavy rain flooded the city center and led to chaos in regard to transport in the city center. In mountain areas, lots of rural roads were blocked. In the city center, there were more than 95 road links blocked by deep ponding. Figure 4 illustrates the distribution of the main ponded areas in Beijing. We can conclude that Beijing’s 2nd, 3rd, 4th and 5th ring roads were blocked. Most ponded areas were in the rapid ring roads and concave-type overpasses, which made the city’s arterial roads come to a standstill (Figures 4, 5, and 6).
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Figure 4 Flood ponding distribution in Beijing after heavy rainfall in July 21st, 2012 (Source: the internet) *Numbers in the figure show the flooded road sections.
Figure 5 Blocked road under Lianhua Bridge
Figure 6 Motorway G4 Changyang section was
because of the flood (Source: Xinhua News
blocked by flood (Source: Xinhua News Agency)
Agency)
In addition to the ground road system, rail transport also came under serious crisis. Because electrical devices were submerged, the Airport Express line’s rail trains lost their power supply. In some subway stations, such as Majiapu and Jiaomenxi, flood water flushed in reverse into the stations, which forced them out of service (Wei, 2012). 3.1.2 Policies The limitation of Jinan's sewerage system’s capacity and the unwise decision of closing the water gates aggravated the disaster. Firstly, in the old urban area of Jinan, the sewerage system was built several decades ago. The main drainage pipe’ diameter is only 300mm. The rainfall was far beyond the sewerage system’s capacity that day. 7
Journal Pre-proof Secondly, to promote tourism in Jinan, the city moat’s water gates were closed to preserve water in the moat. Before the storm, the water gates were still closed. When people opened the water gates, the gates were blocked up by boats from upstream. As all flood channels were either blocked up or up to the limitation, the flood finally stopped at Quancheng Square(Wei, 2011a). Moreover, people were totally unaware of the danger. When the rainstorm happened, people still hid in the busy underground supermarket to shelter themselves from the rain. Outside the door, there was a moat that was already flooding. When the moat began to pour into the underground supermarket , the crowd began to flee in complete disorder. As that of Jinan, Beijing's sewerage system had been in poor condition. Investment in an urban sewerage system cannot bring immediate benefits and achievements to the government, so local governments instead prefer to invest public funds in municipal infrastructure related to real estate and industrial projects. Also, people in Beijing were ignorant about the turbulent flood caused by the storm. People were washed away or fell into wells almost in a matter of moments on the road; others were too late to respond to rescue. Learning from these disasters caused by heavy rain, we recommend the following targeted policies. For mitigation policies, first as a hard infrastructure, the renovation of the drainage system is necessary. The capacities of sewerage systems in Jinan and Beijing have not kept up with rainfall drainage needs, which is the leading cause for water accumulation. For an international metropolis like Beijing, flood prevention infrastructure and pumping system must be in accordance with the development, otherwise, the casualties and economic losses caused by heavy rain will be huge. Also, some disaster prevention facilities such as sandbags could be prepared in subway stations. Second as a soft measure, great importance should be attached to education, especially for women, children and the elderly, who are vulnerable in climate disasters. Continuous education and enlightenment can plant in people’s mind a good awareness to avoid the future possible big risk. For adaptation policies, the first is to establish a sound pre-caution system. During the rainy season, rain time and location forecasts could be spread through mass media like TV news, WeChat and Micro-blog to alert people. Maps of flooded roads could help travelers to avoid choosing routes with low-lying areas and rescue organizations to take actions more effectively. Then, police officers need to play a timely role. Traffic policemen should direct traffic in time when congestion occurs, especially when street lights and signal lights fail. The security policemen should rescue the car owners in time when they are trapped during heavy rain. Next, it is also necessary to publicize self-help knowledge. Through mass media, government and organization officials could publish self-help common sense guidebooks, etc., Even a five-minute reading of these texts could save a life when trapped in a car by floods.
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Journal Pre-proof 3.2 Case Study Concerning the Impact of Ice and Snow Weather on Transport 3.2.1 Phenomena Evidences Compared to heavy rain, the case of ice and snow weather can influence transport both in spatially wider areas and temporally longer periods. Ice and snow weather mainly decreases friction between road surface and tires. In south China, the road system has frequently suffered from ice rain in winter in recent years. Road surfaces are covered by about 2mm thick ice when ice rain comes. It often causes serious traffic accidents, as drivers can hardly notice the ice surface. Even though accidents could be avoided via drivers’ alerts, road capacity decreases considerably. From January 10th to February 2nd, 2008, China’s southern region suffered from serious ice and snow weather four times. The rare weather hit nearly 20 provinces. The weather seriously damaged transport infrastructure, energy supply and power transmission devices and agricultural production. In regard to provincial and intercity transport, because the ice and snow weather occurred just during the Spring Move, a time of heavy passenger transport around Chinese Lunar New Year, passengers on their way hometowns were seriously influenced by the bad weather. Due to electrical conductor icing, trains on Beijing-Guangzhou railway were stuck because of power loss. At one point, there were about 300,000 passengers at the Guangzhou railway station. Motorways in China’s southern region were mostly closed due to the bad weather. Influenced by motorway closings, national roads and provincial roads suffered much more vehicles beyond capacity (Figure 7 and Figure 8). At the most serious time, 40,000km of over 21 national roads were in the traffic jam, which caused thousands of people and vehicles to be stuck on their journeys. Air transport was also profoundly influenced by bad weather. Airport runways and aircrafts were covered by thick ice, and 19 airports in the southern region were closed for a long time (Zhang, 2013).
Figure 7 Traffic jams at Wuhan Yangtze River
Figure 8 Jingzhu Motorway Hunan section was in
Bridge Wuchang side due to ice and snow
an entirely standstill due to ice cover on roads,
weather, January 14th, 2008 (Source: Xinhua
January 30th, 2008 (Source: Xinhua News
News Agency)
Agency)
With regard to urban transport, icing weather covered road surface and made them extremely slippery, especially at bridges. As bridges are always the arterial 9
Journal Pre-proof channel in urban transport systems, once they are closed, the whole transport system operation stops. In mid-January 2008, many bridges crossing the Yangtze River and the Xiang River, such as the Jiujiang Yangtze River Bridge and the Changsha Xiang River Bridge, were closed for some periods. Each time the authorities closed a bridge, hundreds of vehicles were blocked. Besides ice cover, snow cover also largely influences the transport systems. In January 2010, the Aletai and Tacheng regions in Xinjiang province were hit by strong snow storm four times continuously, which happens only once in 60 years. Even into March 2010, the regions were suffering from heavy snow and strong wind again (Wei, 2011b). Heavy snow and strong wind mainly influence transport on national roads and provincial roads. Because of Xinjiang’s side land, yet sparse population distribution, snow cover on national and provincial roads could not be cleared easily (Figure 9 and Figure 10). On March 7th, 2010, in Yumin County, provincial roads No. 222 and No. 317 to the capital city of Urumqi were closed due to snow cover. All roads connecting the Yumin County center to its 30 villages were blocked. In March 8th in Fuyun County, more than 200 vehicles and 500 people were blocked on national road No. 216. On the following day, all roads passing Yumin County were blocked, and the county became an isolated island (Xiao, 2010).
Figure 9 Provincial road was blocked by snow, March 2010 ( Source: Urumqi online)
Figure 10 Heavy snow with strong wind buried tracks at Aikenda mountain slope in Xinjiang, 2010 ( Source: China Youth Daily)
3.2.2 Policies In the face of ice and snow, people often can only wait for them to melt away. Also, governments prefer to shut down some motorways and bridges to avoid traffic accidents, which brings pressure on the remaining road networks, increasing traffic congestions and making it difficult for people to travel. Having learnt from the cases of disasters caused by ice and snow, we propose the following targeted policies. For mitigation policies, first of all, intelligent means can be used on some critical bridges and motorways. Melting snow and ice by itself and removing it through drainage systems is a long process. Human intervention will accelerate this process and shorten the scope and time of traffic impact. Sensors can be set up on the 10
Journal Pre-proof road surface to collect real-time information of ice and snow, then deice and melt snow using automatic snow-melting agent spraying systems. Such timely measures provide security guarantees without having to close major motorways and bridges. Also, education needs to be emphasized as we recommended in the case of rain disasters, to make people aware of the dangers of ice and snow. For adaptation policies, first of all, as hard measures, snow-chains or snow tires could be installed for safety. Slippery roads may cause serious accidents, and this measure could ease the decrease of friction. Other policies are similar to those for rain disasters. As soft measures, pre-caution system is an essential measure. Snow time and location forecasts, and icy road maps are helpful to travelers and the agents responsible for cleaning ice and snow on roads. Traffic policemen also need to guide people and cars in time, and to conduct accident rescue. Next, safety education could be increased by using media propaganda to spread messages such as “Obey the traffic rules”, “Slow down and keep a safe distance from the vehicles ahead” and “During snow days, do not walk with hands in pockets due to the cold, it is easy to lose balance.” 3.3 Case Study Concerning the Impact of Fog and Haze on Transport 3.3.1 Phenomena Evidences Fog and haze weather mainly affects air transport, motorways and urban expressways. They mainly affect visibility, which may slow down vehicles and reduce road capacity and average speed accordingly. When obstacles are in front of travelers because of the limited visible distance, accidents are natural to occur. In 2013, from January to February, northern China faced long lasting fog and haze weather. In January alone, there were 27 fog and haze weather days out of 31days. One of the most seriously influenced provinces was Hebei province. In January, from the 11th to 17th, 21st to 24th, and 27th to 30th, heavy fog continuously hit the area. In the capital city Shijiazhuang, the fog and haze lasted for more than 20 hours on January 22nd. Heavy fog and haze led to low visibility down to less than 100 meters, for the whole day. The airport and all 22 motorways were entirely closed. All flights were canceled. In the city center, the number of traffic accidents increased a lot, and average speed on the road network was notably lower than its usual levels (Tang, 2013). Beijing was also influenced by serious fog and haze in January, 2013. Especially on January 31st, heavy fog hit the city along with ice and snow. From 12a.m. to 11a.m. alone, there were more than 2000 traffic accidents. Although the accidents were mostly light, they triggered a chaos in the whole transport system. For example, on the overhead road from Wangjing to Taiyanggong which is about 3km long, more than 100 cars were involved in a pileup accident. There were 12 accidents on Jingping motorway from the 44km point to the 45km point. On North 4th ring road, wet road and bad visibility caused 12 accidents involving 40 cars, which caused more than 2 hours of serious congestion in the direction from east to west (Yan, 2013). 11
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Figure
11
Congestion
at
Motorway
G4
Figure 12 100 cars pileup at overhead road from
Shijiazhuang Entrance due to heavy fog and haze,
Wangjing to Taiyanggong, Beijing, January,
January 2013(Source: China News Agency)
2013 (Source: Jinwan internet community)
3.3.2 Policies For fog and haze, most of the policies taken by the government involve closing some high-pollution factories to avoid worse visibility, but this did not work very well. Having learned from the cases of disasters caused by fog and haze, we propose the following targeted policies. For mitigation policies, fog is difficult to be eliminated by human means, so the best way is to awaken people to the dangers of fog and haze through mass media. To reduce carbon emissions, governments should advocate people to travel by public transport as a preferred way. For adaptation policies, first of all, timely vehicle glass defogging by cold air could ease the impacts of low visibility. Other policies (policemen, pre-caution system, education) are similar to policies for rain and snow disasters. Information about reasonable use of car lights, speed limit, and route choice could be advised before fog and haze. What’s more, do not drive on the roadside, to avoid hitting the fence and collision with vehicles parked in the emergency lane.
4. STRATEGIES AND POLICIES FOR TRANSPORT CONGESTION AND ACCIDENTS PREVENTION IN ABNORMAL BAD WEATHER To continuously improve the level of traffic safety, and ensure the efficiency of the transport systems in abnormal bad weather, relevant departments must seize two priorities: one is to create a reliable transport system, the second is to achieve a deep integration of traffic and meteorology. Some recommendations are as follows: 4.1 Create a reliable transport system On the one hand, even though abnormal weather may cause congestion in a large area, congestion is caused by chaos in several intersections and road links. For 12
Journal Pre-proof instance, in Beijing, heavy storms in the summer always cause floods on main roads. Under concave-type overpasses, such as the Lianhua Bridge and the Guangqu gate overpass, floods block the traffic. These critical points block the whole road and paralyze the whole transport system into. Therefore, via in-depth analysis of essential aspects and transport network planning based on reliability, city disaster prevention and mitigation ability could be improved. Simultaneously, a detailed evaluation of the current transport system is also necessary. Workers and devices should be arranged in advance at critical points for immediate responses when disaster comes On the other hand, serious transport paralyzes are always caused by break-down of transport infrastructure. Therefore, proper improvement of infrastructure design and planning standards would fundamentally improve the ability of disaster prevention and mitigation in the transport field.
4.2 Achieving a deep integration of traffic and meteorology Traffic operation and safety are closely related to the meteorological department. Based on big data cloud computing, traffic departments should vigorously promote the full integration of traffic and meteorological data. In the view of personalized and diversified traffic needs, providing accurate traffic meteorological services, including monitoring, forecasting, warning and automatic processing is essential. Efforts can be carried on regarding the following aspects: (1) Formulate a specific development strategy at the national level as soon as possible. (2) Steadily increase investment in the field of traffic meteorological monitoring, and enhance the coordination of traffic and meteorological departments. (3) Speed up the step of the construction of traffic meteorological information collection and early warning system which can a) judge and evaluate weather conditions and transport infrastructure performance accurately, and b) respond rapidly to the problems, warning the relevant departments as well as the road users and automatic processing. (4) Strengthen the standardization work and develop a common specification to ensure the connection between the associated equipment and achieving the mutual transmission of information.
4.3 Prepare Complete Pre-arranged Plans for Abnormal Issues Nowadays, in China, most pre-arranged plans focus on traffic accident rather than on traffic congestion caused by extreme weather. In 2008, when heavy ice rain and snow hit southern China, some provinces had no pre-arranged plan against ice and snow weather at all. The absence of plans not only created confusion among different government departments, but also created delays and lost precious time for 13
Journal Pre-proof rescuers. When disasters come, each government department should understand and keep its own duties and then share valuable information with other departments. Based on pre-arranged plans, leader groups should be set immediately. On the one hand, to keep rapid responses, each region and department’s responsibility should be clear and defined in advance. On the other hand, possible risk points should be thoroughly estimated. For each possible risk point, a corresponding strategy is necessary, to keep emergency response productive. 5. CONCLUSION Having examined the case studies, we have found the following typical phenomena and mechanisms of disasters influencing on the transport and traffic. 1) Heavy rain: slippery road surface and low visibility made drivers slow down. Moreover, without well-functional sewerage systems, roads were blocked by deep ponding. 2) Ice and snow: due to the influence of motorway closures and the decrease of friction between road and tire, ordinary roads were more prone to traffic congestion. 3) Fog and haze: low visibility always caused continuous rear-end accidents. After examining the mechanisms, the following two-phase policies are recommended. Mitigation policies are to be implement before disasters, and adaptation policies are alleviate the impacts after the disaster occurrence. a) Mitigation policies for infrastructure: enhance disaster prevention facilities (e.g. sandbags), sewerage system, pumping systems and intelligent snow-melting agent spraying system. b) Mitigation policies for people: introduce pre-education methods. They can be propagated through mass media such as TV news, WeChat and Micro-blog. c) Adaptation policies for infrastructure: strengthen pre-caution systems, which will be a guide for travelers, rescue organizations and governments. d) Adaptation policies for people: increase safety education through media propaganda to encourage self-help and mutual help. Police officers need to play a timely role in traffic guidance and rescue. REFERENCES 1. 2.
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Journal Pre-proof 19. YAN, B. (2013). Heavy traffic accidents on Beijing's roads [Online]. CCTV News. Available: http://news.cntv.cn/2013/02/01/ARTI1359662277230464.shtml [Accessed 06-12 2019]. (in Chinese) 20. YANG, Z., LIN, Y. & GAO, X. (2010). Urban Expressway Capacity Under Adverse Weather Conditions. Journal of Transport Information and Safety, 28, 75-78. (in Chinese) 21. ZHANG, C., ZHANG, L.-N., CHENG, C.-L. & WANG, B.-Z. (2007). Research Status and Future Trend of Expressway Meteorological Forecast System. Journal of Tropical Meteorology 652-658. (in Chinese) 22. ZHANG, H. (2013). Snow Disaster in Southern China in 2008 [Online]. CAIXIN.COM. Available: http://special.caixin.com/event_0110/ [Accessed 06-14 2019]. (in Chinese) 23. ZHAO, H., WANG, W., LI, Z. & WANG, Y. (2010). Adverse Effects of Fog on China's Transportation and Countermeasures. Journal of meteorology and environment, 26, 58-62. (in Chinese)
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Journal Pre-proof Highlight 1. Classifying different weather conditions and pre-arranged plans are very critical. 2. To create a reliable transportation system is a priority to disaster prevention. 3. Mitigation and adaptation policies can ease the impacts of abnormal bad weather.